Diagnosis of panhypopituitarism

In typical cases, the diagnosis of panhypopituitarism is simple. The appearance of a complex of symptoms of hypocorticism, hypothyroidism, and hypogonadism after complicated childbirth or due to another cause indicates hypothalamic-pituitary insufficiency. Timely diagnosis is delayed in patients with sluggish Sheehan syndrome, although the absence of lactation after childbirth accompanied by hemorrhage, prolonged loss of work capacity, and menstrual dysfunction should suggest hypopituitarism.

A number of laboratory parameters are of diagnostic value. Hypochromic and normochromic anemia may be observed, especially in severe hypothyroidism, sometimes leukopenia with eosinophilia and lymphocytosis. When combined with diabetes insipidus, hypopituitarism is accompanied by low relative density of urine. The blood glucose level is low, and the glycemic curve with glucose load is flattened (hyperinsulinism). The cholesterol content in the blood is increased. The proportion of adenohypophyseal hormones (ACTH, TSH, STH, LH and FSH) decreases in the blood and urine.

In the absence of the possibility of direct determination of hormones, indirect tests can be used. Thus, the ACTH reserve in the pituitary gland is estimated by the test with metopirone (Su=4885), which blocks the biosynthesis of cortisol in the adrenal cortex, and by the mechanism of negative feedback, causing an increase in the ACTH level in the blood. Ultimately, the production of corticosteroids, precursors of cortisol, mainly 17-hydroxy- and 11-deoxycortisol, increases. Accordingly, the content of 17-OCS in the urine increases sharply. In hypopituitarism, there is no significant reaction to the introduction of metopirone. The test is performed as follows: 750 mg of the drug in granules is administered orally every 6 hours for 2 days. The content of 17-OCS in daily urine is analyzed before the test and on the second day of taking metopirone.

The initial level of corticosteroids in the blood and urine is usually reduced. With the introduction of ACTH, the content of corticosteroids increases, unlike in patients with Addison's disease, i.e. primary hypocorticism. However, with a long duration of the disease, the reactivity of the adrenal glands to the introduction of ACTH gradually decreases. The presence of hypogonadism in women is indicated by a decrease in the level of estrogens, and in men - testosterone in the blood and urine.

Low basal metabolism, decreased blood levels of protein-bound iodine or butanol-extractable iodine, free thyroxine, triiodothyronine, thyroid-stimulating hormone, and ¹³¹ I absorption by the thyroid gland indicate a decrease in its functional activity. The secondary nature of hypothyroidism is confirmed by an increase in the accumulation of ¹³¹ I in the thyroid gland and in the level of thyroid hormones in the blood after the administration of thyroid-stimulating hormone.

Differential diagnosis of panhypopituitarism is not always simple. A number of diseases that lead to weight loss (malignant tumors, tuberculosis, enterocolitis, sprue and sprue-like syndromes, porphyria) must be differentiated from hypothalamic-pituitary insufficiency. However, exhaustion in the above diseases, unlike hypothalamic-pituitary insufficiency, develops gradually, is the outcome of the disease, and not its dominant manifestation; only in case of impaired absorption in the intestine (sprue, enterocolitis, etc.) can exhaustion be accompanied by secondary endocrine insufficiency.

The severity of anemia sometimes provides grounds for differential diagnosis with blood diseases, and severe hypoglycemia can stimulate pancreatic tumors - insulinomas.

Primary hypothyroidism is excluded by a low level of thyroid-stimulating hormone in the blood and an increase in the functional activity of the thyroid gland with the introduction of exogenous thyroid-stimulating hormone.

Differential diagnosis of panhypopituitarism is especially difficult in cases where primary hypothyroidism is complicated by disorders in the sexual sphere and with peripheral polyendocrine insufficiency (Schmidt syndrome), which includes primary autoimmune damage to the adrenal glands, thyroid gland and often the gonads.

In clinical practice, the most relevant differentiation of pituitary cachexia from exhaustion due to psychogenic anorexia, which occurs in young girls and very rarely in young men due to a psychotraumatic conflict situation or an active desire to lose weight and forced refusal of food. Decreased appetite up to a complete aversion to food is accompanied in psychogenic anorexia by a violation or disappearance of menstruation even before the development of severe exhaustion. The sexual apparatus gradually atrophies, functional disorders of the gastrointestinal tract and multiple symptoms of endocrine insufficiency occur. The decisive factor in differential diagnostics is the anamnesis, the preservation of physical, intellectual and sometimes even creative activity with an extreme degree of exhaustion, the preservation of secondary sexual characteristics in combination with deep atrophy of the genitals.

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